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Resources Science news story. Word bank. Activity 1: Mixed-up meanings. Activity 2: Comprehension. Activity 3: Find the missing word. Activity 4: What kind of statements? Activity 5: Topics for discussion, research or presentation.

NewsUniversity of Texas at Austin: 26-Nov-2007 17:00 Eastern US Time

Big bang for flowersThe Tree of Life for flowering plants has been drawn using the largest ever set of data.

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Scientists have found that the two largest groups of flowering plants are more closely related to each other than to any of the other groups. They are grasses and their relatives (monocots) and sunflowers and tomatoes (eudicots). The scientists work at the University of Texas at Austin and the University of Florida.

Their research also confirmed that a plant found only on the Pacific island of New Caledonia, represents the earliest lineage of flowering plants. The plant is called Amborella.

Robert Jansen is professor of integrative biology at The University of Texas at Austin. He says that this new work sets the stage for all future comparative studies of flowering plants.

“If you are interested in understanding the evolution of flowering plants, you can’t do that unless you understand their relationships.”

The University of Florida team was led by Doug and Pam Soltis. They showed that the major diversification of flowering plants took place over the comparatively short period of less than five million years. This produced all the major lines of flowering plants that exist today.

This diversification was so stunning that the scientists are calling it the “Big Bang,”

“Flowering plants today comprise around 400,000 species,” said Pam Soltis. She is curator at the university’s Florida Museum of Natural History. “To think that the burst that gave rise to almost all of these plants occurred in less than five million years is pretty amazing.”

Especially when you consider that flowering plants as a group have been around for at least 130 million years, she added.

The details of the rapid diversification of flowering plants have always been puzzling. Charles Darwin himself called their evolutionary history an “abominable mystery.”

One of the reasons for the puzzle is that it all happened in a very short period. But by analysing DNA sequences, the scientists have made the picture much clearer.

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They did it like this: Jansen and his colleagues at The University of Texas at Austin analysed DNA sequences of 81 genes. These were found in the chloroplast genome of 64 species of plants. Meanwhile the Florida researchers analysed 61 genes from 45 species of plants.

The two groups then did a combined analysis. This produced evolutionary trees that had all the major groups of flowering plants.

But there is still a mystery. We now know what happened. But we don’t know why.

There might have been a major change in climate, say Pam and Doug Soltis. Or a new evolutionary trait might have been so effective that it gave a big kick to plant growth. This might well have been a more efficient cell that moves water up plant stems.

This cell type is not present in the first three flowering plant lineages, said Doug Soltis, professor of botany at Florida.

###

The scientists’ work is funded by two grants from the Tree of Life program at the National Science Foundation.

475 wordsFlesch reading ease: 57Flesch-Kincaid Grade level: 8.9

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Word bankPupils will not know some of the words used in the text. Meanings are given below, followed by an exercise in matching words and meanings.

Teachers may choose to provide some or all of the meanings to help pupils read and understand the story. An approach that leads to better learning is to ask pupils to complete as much of Activity 1 as possible during their first encounter with the text.

By tackling this exercise and those that follow – which are known collectively as directed activities related to texts (DARTs) – pupils can engage with a piece of writing, and learn a great deal from it, even when many of its ideas and words are unfamiliar to them.

Word Meaning1 data pieces of information; measurements2 research careful study to find out facts or information3 confirmed showed something was true4 represents is an example of5 lineage all the members of a family through time,

that came from one ancestor in the past6 professor a university teacher of the highest level7 integrative pulling things together8 biology the science of life and living things9 comparative to do with comparing things10 evolution how species alter over time, through small

changes that help individuals to survive and produce healthy young

11 relationships how things are connected12 major very important13 diversification occurring in many more varieties14 comparatively compared with other things of the same kind15 comprise consist of16 curator person in charge of a museum or collection17 evolutionary through evolution18 abominable very bad or unpleasant19 analysing undefined20 DNA giant molecule that contains the genes; short

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for deoxyribonucleic acid21 sequences the order of the parts in a piece of DNA.

Some of these are genes22 colleagues people who work together23 analysed studied the parts something is made of, and

how they work together24 chloroplast tiny structure in green plants that contains

chlorophyll25 genome the full set of genes carried by an individual

or species26 species group of individuals that are like each other

and can breed together to produce fertile young

27 researchers people who study something carefully to learn more

28 genes parts of animal and plant cells that control what is inherited; sections of DNA that do a particular job

29 combined joined together30 analysis detailed examination or separation into parts31 climate average weather over a long period32 trait a feature that can be passed on33 effective producing the effect that is wanted34 efficient doing work well; effective35 lineages all the members of families through time,

that came from one ancestor in the past36 botany the scientific study of plants37 ancestor member of the same family that lived in the

past38 cell the building block of all living things except

viruses39 chlorophyll green substance in plants that is important

for photosynthesis40 DNA giant molecule that contains the genes; short

for deoxyribonucleic acid41 evolution how species alter over time through small

changes that help individuals survive and produce healthy young

42 fertile able to produce young43 genes parts of animal and plant cells that control

what is inherited; sections of DNA that do a particular job

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44 molecule the smallest part of a substance; made of two or more atoms joined together

45 species group of individuals that are like each other and can breed together to produce fertile young

46 photosynthesis process by which green plants trap light energy from the Sun, and convert it to food and carbon dioxide

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Activity 1 Mixed-up meaningsPupils should try to fill in the blanks in the final column with the words that match the meanings. The words needed are listed, but not necessarily in the right order, in the first column.

This exercise should not be tackled in isolation, but by a reader with access to the story itself: The contexts in which words are used provide powerful clues to their meanings.

Word Meaning Word should be1 data pieces of information;

measurements2 research to do with comparing things3 confirmed undefined4 represents giant molecule that contains

the genes; short for deoxyribonucleic acid

5 lineage the smallest part of a substance; made of two or more atoms joined together

6 professor showed something was true7 integrative tiny structure in green plants

that contains chlorophyll8 biology people who study something

carefully to learn more9 comparative joined together10 evolution the science of life and living

things11 relationships studied the parts something is

made of, and how they work together

12 major the full set of genes carried by an individual or species

13 diversification a feature that can be passed on14 comparatively member of the same family

that lived in the past15 comprise how things are connected16 curator all the members of families

through time, that came from one ancestor in the past

17 evolutionary through evolution

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18 abominable consist of19 analysing person in charge of a museum

or collection20 DNA very bad or unpleasant21 sequences giant molecule that contains

the genes; short for deoxyribonucleic acid

22 colleagues how species alter over time, through small changes that help individuals to survive and produce healthy young

23 analysed average weather over a long period

24 chloroplast the building block of all living things except viruses

25 genome producing the effect that is wanted

26 species very important27 researchers the scientific study of plants28 genes parts of animal and plant cells

that control what is inherited; sections of DNA that do a particular job

29 combined all the members of a family through time, that came from one ancestor in the past

30 analysis is an example of31 climate the order of the parts in a

piece of DNA. Some of these are genes

32 trait green substance in plants that is important for photosynthesis

33 effective process by which green plants trap light energy from the Sun, and convert it to food and carbon dioxide

34 efficient occurring in many more varieties

35 lineages people who work together36 botany detailed examination or

separation into parts

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37 ancestor parts of animal and plant cells that control what is inherited;

sections of DNA that do a particular job

38 cell compared with other things of the same kind

39 chlorophyll group of individuals that are like each other and can breed together to produce fertile young

40 DNA group of individuals that are like each other and can breed together to produce fertile young

41 evolution careful study to find out facts or information

42 fertile a university teacher of the highest level

43 genes able to produce young44 molecule pulling things together45 species doing work well; effective46 photosynthesis how species alter over time

through small changes that help individuals survive and produce healthy young

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Activity 2 Comprehension 1. A Tree of Life for flowering plants already existed. What is different

about this new research?

2. What did the scientists find out about the two largest groups of

flowering plants?

3. What are the two largest groups of flowering plants called (either

scientific or common names)?

4. What makes Amborella a special plant?

5. If a scientist wants to study the evolution of plants what does she need

to understand?

6. What does 'major diversification' mean?

7. What is so stunning about this diversification?

8. What is it we don't understand about the diversification?

9. What set of techniques did the scientists use in their research?

10.The scientists obtained detailed knowledge of the genes of how many

plants altogether?

11.The scientists produced an evolutionary tree from their detailed

knowledge of the genes. In your own words what is an evolutionary

tree?

12.The article does not explain how the scientists got from the new

knowledge of the genes to the evolutionary tree. Can you suggest

why it does not?

13.We know more now about the details of the diversification, but we

still don't know what?

14.A couple of suggestions are made in the second last paragraph. How

could the scientists decide which if any of these is true?

15.Can you think of any other possible explanation?

16.How could you test your explanation?

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Activity 3 Find the missing wordPupils should try to fill in the blanks using clues from the rest of the sentence. When in doubt, the length of each blank indicates the length of the missing word. A complete list of words that belong in the blanks is provided at the end of the passage.

Big bang for flowersThe Tree of Life for flowering ______ has been drawn using the largest ever set of ____.

Scientists have found that the two largest groups of _________ plants are more closely related to each other than __ any of the other groups. They are grasses and _____ relatives (monocots) and sunflowers and tomatoes (eudicots). The scientists ____ at the University of Texas at Austin and the __________ of Florida.

Their research also confirmed that a plant found ____ on the Pacific island of New Caledonia, represents the ________ lineage of flowering plants. The plant is called Amborella.

Robert ______ is professor of integrative biology at The University of _____ at Austin. He says that this new work sets ___ stage for all future comparative studies of flowering plants.

"If ___ are interested in understanding the evolution of flowering plants, ___ can't do that unless you understand their relationships."

The University __ Florida team was led by Doug and Pam Soltis. ____ showed that the major diversification of flowering plants took _____ over the comparatively short period of less than five _______ years. This produced all the major lines of flowering ______ that exist today.

This diversification was so stunning that ___ scientists are calling it the "Big Bang,"

"Flowering plants _____ comprise around 400,000 species," said Pam Soltis. She is _______ at the university's Florida Museum of Natural History. "To _____ that the burst that gave rise to almost all __ these plants occurred in less than five million years __ pretty amazing."

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Especially when you consider that flowering plants __ a group have been around for at least 130 _______ years, she added.

The details of the rapid diversification of _________ plants have always been puzzling. Charles Darwin himself called _____ evolutionary history an "abominable mystery."

One of the reasons for ___ puzzle is that it all happened in a very _____ period. But by analysing DNA sequences, the scientists have ____ the picture much clearer.

They did it like this: Jansen ___ his colleagues at The University of Texas at Austin ________ DNA sequences of 81 genes. These were found in ___ chloroplast genome of 64 species of plants. Meanwhile the _______ researchers analysed 61 genes from 45 species of plants.

The two groups then did a combined analysis. This ________ evolutionary trees that had all the major groups of _________ plants.

But there is still a mystery. We now know ____ happened. But we don't know why.

There might have been _ major change in climate, say Pam and Doug Soltis. __ a new evolutionary trait might have been so effective ____ it gave a big kick to plant growth. This _____ well have been a more efficient cell that moves _____ up plant stems.

This cell type is not present __ the first three flowering plant lineages, said Doug Soltis, _________ of botany at Florida.

These are all the words that belong in the blanks:a, analysed, and, as, curator, data, earliest, Florida, flowering, flowering, flowering, in, is, Jansen, made, might, million, million, of, of, only, Or, place, plants, plants, produced, professor, short, Texas, that, the, the, the, the, their, their, They, think, to, today, University, water, what, work, you, you

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Answer Key:


Scientists have found that the two largest groups of flowering plants are more closely related to each other than to any of the other groups. They are grasses and their relatives (monocots) and sunflowers and tomatoes (eudicots). The scientists work at the University of Texas at Austin and the University of Florida.


Robert Jansen is professor of integrative biology at The University of Texas at Austin. He says that this new work sets the stage for all future comparative studies of flowering plants.

"If you are interested in understanding the evolution of flowering plants, you can't do that unless you understand their relationships."


This diversification was so stunning that the scientists are calling it the "Big Bang,"

"Flowering plants today comprise around 400,000 species," said Pam Soltis. She is curator at the university's Florida Museum of Natural History. "To think that the burst that gave rise to almost all of these plants occurred in less than five million years is pretty amazing."


The details of the rapid diversification of flowering plants have always been puzzling. Charles Darwin himself called their evolutionary history an "abominable mystery."

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But there is still a mystery. We now know what happened. But we don't know why.



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Activity 4 What kind of statement?Students should read the news story on page 1 about the latest scientific research, and highlight phrases or sentences according to the following key (or any other way of indicating the different types of statement that can be done with the resources in their pockets or in your classroom):

Existing knowledgeAims/reasons for doing the researchTechnology and methodsNew findings or developmentsHypothesisPredictionEvidenceIssues, implications and applicationsIssues, implications and applications

Normally no more than one phrase or sentence should be highlighted in each paragraph, unless the reader decides that a particular paragraph contains several really important ideas.

Usually the decision will not be too difficult. But choosing between, say, hypotheses and new findings can sometimes be tricky. There isn’t always an obviously right or wrong answer, even to the scientists themselves.

Pupils should be encouraged not to agonise too long over their choice of statement type, but to be prepared to give reasons for their decisions.

Note: A hypothesis is a “tentative explanation that leads to predictions that can be tested by experiment or observation”.

Answer Key: (These are illustrative choices. There are many others.)


Scientists have found that the two largest groups of flowering plants are more closely related to each other than to any of the other groups. They are grasses and their relatives (monocots) and sunflowers and tomatoes

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(eudicots). The scientists work at the University of Texas at Austin and the University of Florida.


Robert Jansen is professor of integrative biology at The University of Texas at Austin. He says that this new work sets the stage for all this new work sets the stage for all future comparative studies of flowering plants.future comparative studies of flowering plants.

“If you are interested in understanding the evolution of flowering If you are interested in understanding the evolution of flowering plants, you can’t do that unless you understand their relationshipsplants, you can’t do that unless you understand their relationships.”


This diversification was so stunningThis diversification was so stunning that the scientists are calling it the “Big Bang,”

“Flowering plants today comprise around 400,000 species,” said Pam Soltis. She is curator at the university’s Florida Museum of Natural History. “To think that the burst that gave rise to almost all of these the burst that gave rise to almost all of these plants occurred in less than five million years is pretty amazing.” plants occurred in less than five million years is pretty amazing.”


The details of the rapid diversification of flowering plants have always been puzzling. Charles Darwin himself called their evolutionary history an “abominable mystery.”



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But there is still a mystery. We now know what happened. But we We now know what happened. But we don’t know why.don’t know why.



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Activity 5 Topic for discussion, research or pupil presentations

Here some of the issues, implications and applications taken directly from the text:

1. The Tree of Life for flowering plants has been drawn using the

largest ever set of data.

2. This new work sets the stage for all future comparative studies of

flowering plants.

3. If you are interested in understanding the evolution of flowering

plants, you can’t do that unless you understand their relationships.

4. This diversification was so stunning that the scientists are calling it

the “Big Bang,”

5. To think that the burst that gave rise to almost all of these plants

occurred in less than five million years is pretty amazing – especially

since flowering plants have been around for at least 130 million

years.

6. The details of the rapid diversification of flowering plants have always

been puzzling. Charles Darwin himself called their evolutionary

history an “abominable mystery.”

7. But there is still a mystery. We now know what happened. But we

don’t know why.

8. There might have been a major change in climate, or a new

evolutionary trait might have been so effective that it gave a big kick

to plant growth. This might well have been a more efficient cell that

moves water up plant stems.

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Here are some possible topics for group discussion, research or presentations arising from the above. Students should be encouraged to think up others themselves:

1. What do the scientists mean by a Tree of Life?

2. How could we decide if this statement is true or simply one team of

scientists talking up the importance of their own work?

3. Working in groups students should try to figure out what this

statement means and why it is true. To do so they will need to explore

a little, and a good place to start is

www.phylo.org/sub_sections/outreach.php

4. What does the Big Bang usually refer to? Why is this a good name in

this case? Why is it not a good name?

5. A timescale on which 5 million years is a short time is very unfamiliar

and hard to grasp. Students should work together to prepare some kind

of visual demonstration of the history plants on life on Earth. Good

ideas and information at

www.teachersdomain.org/resources/ess05/sci/ess/earthsys/walloftime/

index.html and

http://serc.carleton.edu/quantskills/methods/quantlit/DeepTime.html

6. Darwin's choice of the word "abominable" seems rather strange to us

now. Explain what he means and why you think he chose that

particular word.

7. How could we find out what happened? Can we know?

8. How would scientists normally decide between two different

hypotheses to explain the same thing? Can they do this here? What

can they do?

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Tips for science class discussions and groupwork

No 65

Research evidence is clear about the kind of classroom discussion that can help to support the development of the kinds of reasoning required for developing and using understanding …Alexander's 'dialogic teaching' involves creating a learning environment in which students learn together … listen to one another's ideas, share ideas and consider alternative viewpoints. The learning environment is a supportive one in which students can articulate their ideas freely. Learning is cumulative in that the teachers and students build on their own and each other's idea. Learning is also purposeful, being directed by the teacher towards particular educational goals.

King's College, London (2007) Beyond Fair Testing. London: Gatsby Science Enhancement Programme.

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